Patent Literature 1: JP-2002-097272 A
Patent Literature 2: JP-2003-217339 A (US 2004/0151983 A)
Proton-exchange membrane fuel cell systems are desirably simplified and prepared at lower cost. This demands electrolyte materials that operate at an operating temperature of 100° C. or higher in an atmosphere with no or little humidification. In contrast, customary proton-exchange membrane fuel cells each include an electrolyte that performs ionic conduction by water as proton carrier. The electrolyte is represented by perfluorinated sulfonic acid polymers. The customary proton-exchange membrane fuel cells thereby fail to exhibit satisfactory ionic conduction under operation conditions at a temperature of 100° C. or higher with no or little humidification.
Sol-gel porous glass (Patent Literature 1) and a phosphate hydrogel (Patent Literature 2) have been known as electrolyte materials that less suffer from evaporation of water even at high temperatures.
The techniques disclosed in Patent Literatures 1 and 2 require humidification up approximately to saturated water vapor pressure so as to suppress water evaporation. The techniques are therefore still insufficient in ionic conductivity and stability under conditions with little humidification. The customary electrolyte materials fail to have satisfactory ionic conductivity and stability under operation conditions at a high temperature of 100° C. or higher with no or little humidification.